Efficient file routing system

ABSTRACT

A method or system for efficiently routing a file located on two or more sources to one or more file recipients connected by a plurality of paths in one or more networks. For each file recipient, one or more predetermined utility functions are evaluated to select the most efficient one of the plurality of paths to use for routing the file to the one or more file recipients, and the file is routed to the one or more file recipient using the selected path. The predetermined utility function may be the estimated operating expense associated with the routing of the file to the one or more file recipients, or the estimated return on investment for improving the routing of said file to the one or more recipients, or is related to an estimated file transfer time to the one or more file recipients.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of and claims priority toU.S. patent application Ser. No. 15/053,065, filed Feb. 25, 2016, whichis hereby incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present disclosure relates to communication data networks and theiruse in the efficient transmission of large data files from a source toone or more recipients.

BRIEF SUMMARY

In accordance with one embodiment, a method is provided for efficientlyrouting a file located on two or more sources to one or more filerecipients connected by a plurality of paths in one or more networks.The method evaluates, for each file recipient, one or more predeterminedutility functions to select the most efficient one of the plurality ofpaths to use for routing the file to the one or more file recipients,and routes the file to the one or more file recipient using the selectedpath. The predetermined utility function is preferably the estimatedoperating expense associated with the routing of the file to the one ormore file recipients, or the estimated return on investment forimproving the routing of said file to the one or more recipientsrelative to using another of said one or more path, or is related to anestimated file transfer time to the one or more file recipients.

In one implementation, the evaluating comprises one or more scalingfactor to adjust the relative importance between two or more utilityfunctions, such as a utility function based on quality of experience fora given file transfer, or on expected transfer bitrate for a given filetransfer.

A system may be used to record a plurality of historical utility metricsassociated with the routing of said file to the one or more filerecipients. The evaluating may be done probabilistically based on saidhistorical metrics.

Another implementation may include balancing a load between each of themost efficient one of the plurality of paths for the one or more filerecipients.

In accordance with another embodiment, a system is provided forefficiently routing a file located on two or more sources to one or morefile recipients connected by a plurality of paths in one or morenetworks. The system includes a module coupled with each of the filerecipients to evaluate one or more predetermined utility functions toselect a most efficient one of the plurality of paths to use for routingthe file to the one or more file recipients. The module effects therouting of the file to the one or more file recipients using said theselected paths. The predetermined utility function is preferably theestimated operating expense associated with the routing of said file tothe one or more file recipients, or the estimated return on investmentfor improving the routing of the file to the one or more recipientrelative to using another of said one or more paths, or a utilityfunctions related to an estimated file transfer time to the one or morefile recipients. The evaluating may include one or more scaling factorsto adjust the relative importance between two or more utility functions.

In one implementation, the utility function is based on the quality ofexperience for a given file transfer, or on expected transfer bit ratefor a given file transfer.

The system may be used to record a plurality of historical utilitymetrics associated with the routing of the file to the one or more filerecipients. The evaluating may be done probabilistically based on thehistorical metrics. The system may include balancing a load between eachof the most efficient one of the plurality of paths for each of the filerecipients.

The foregoing and additional aspects and embodiments of the presentdisclosure will be apparent to those of ordinary skill in the art inview of the detailed description of various embodiments and/or aspects,which is made with reference to the drawings, a brief description ofwhich is provided next.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other advantages of the disclosure will becomeapparent upon reading the following detailed description and uponreference to the drawings.

FIG. 1 is a diagrammatic illustration of a network topology for sharingfiles in the prior-art using an origin server (such as a web server) andone or more Content Delivery Networks (CDNs).

FIG. 2 is a diagrammatic illustration of a network topology for sharingfiles using an origin content server (such as a web server), one or moreContent Delivery Networks (CDNs) and a file routing system that includesfile recipients.

FIG. 3 depicts a reverse path in the network topology of FIG. 2 wherebya recipient first requests content and the file routing system selectsan optimal source to send the file.

FIG. 4 is a diagrammatic illustration of the possible paths for thefirst two of multiple file recipients.

While the present disclosure is susceptible to various modifications andalternative forms, specific embodiments or implementations have beenshown by way of example in the drawings and will be described in detailherein. It should be understood, however, that the disclosure is notintended to be limited to the particular forms disclosed. Rather, thedisclosure is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of an invention as defined by theappended claims.

DETAILED DESCRIPTION

FIG. 1 depicts the current state of the art for file sharing over anetwork where one or more recipients 140.1 . . . 140.n require a file135 which originates at a file source 130 and is stored at an originserver 190 and possibly one or more Content Delivery Networks (CDNs)100.1 . . . 100.m. A file is used herein as a generic term comprisingany type of content or shared numerical resource, such as a web pagecontent, a digital movie, etc. File sources 130 and file recipients140.1 . . . 140.n are computing platforms, such as personal computers,servers, laptops or mobile devices. File recipients require contents ofa file which are created and possibly updated a plurality of times atthe file source 130. It should be understood that a file source can alsobe a file recipient and vice versa. The origin server 190 is a serverthat contains the original file.

In the absence of CDNs, the file source 130 transmits the file directly191 to an origin server 190 to create a copy 195. The file recipients140.1 . . . 140.n can then request the file directly 192 from originserver 190.

Each time the file is updated or modified, the file source 130re-transmits the file 130 to the origin server.

As the numbers of file sources and file recipients grow, the load on theorigin server increases and slows performance. Performance issues arefurther aggravated by longer distances and larger files when theserecipients are spread over a large geographic area.

A CDN 100.1 . . . 100.m is a globally distributed network of proxyservers deployed in multiple data centers. The goal of a CDN is to servecontent to end-users with high availability and high performance. Theuse of CDN generally involves contractual agreements based on the amountof bandwidth and/or storage used. Some contracts may include a fixedmonthly fee for a minimum amount of bytes used and a variable fee basedon the number of bytes used that exceed the minimum amount. The fixedand variable fee can be quite high depending on the type of CDN.Typically, CDNs are meant to be used when there is a large community ofusers sharing medium-size files. When the number of users sharing thefile is smaller and the files are extremely large (e.g., movies), theuse of CDNs may not always be the optimal sharing solution.

Content Delivery Networks (CDNs) offer an alternative by storing cachedcopies of the files 130 on a plurality of servers spread over a largegeographic area. In this case, either the file source 130 sends the file135 directly 111.1 . . . 111.m to one or more CDNs 100.1 . . . 100.m orthe origin server 190 sends its copy of the file 195 directly 193.1 . .. 193.m to the CDNs. Each CDN is then responsible for distributing thefile across its own collection of servers.

When a file recipient 140.1 . . . 140.n requests the file 135, therequest is redirected to an appropriate CDN (choice may be based onlocation) which responds directly 112.1 . . . 112.m with a local copy ofthe file 105.1 . . . 105.m.

Since the CDN uses a large number of servers at varying locations in theworld that are sharing the task of serving this file, the response timesare significantly improved over the case where the origin server 190 issolely responsible for delivering the file to all recipients. Asmentioned above, the use of CDNs involves significant costs associatedwith both the storage and distribution of files.

FIG. 2 depicts a network topology that includes a file routing system200 to improve file transfer performance and reduce costs associatedwith using CDNs.

The file routing system 200 domain comprises one or more file routerservers 240, one or more computing platforms acting as file sources 230equipped with a client software 234 and one or more computing platformsacting as file recipients 235.1 . . . 235.n also equipped with a clientsoftware 239.1 . . . to 239.n. In addition, the file routing system 200maintains a file location list 270 which provides a cross-reference ofeach file along with the network addresses of all nodes (file sourcesand file recipients) within the system that have a stored copy of thefile. The system uses a status monitor 245 which ascertains whether filerecipients are presently active on the network using bidirectionalnetwork messaging 246.1 . . . 246.n. A statistic collector module 249may also be used to monitor the performance of the system and optionallyadjust parameters. An administration control module 248 is also providedto configure the system parameters and optimization criteria, such asthe utility and cost functions used for the multi-constraintoptimization as described herein.

The file routing system 200 is designed to optimize the performance andminimize costs for each file transfer and for each recipient or group ofrecipients based on a set of criteria comprising, for example, one ormore of file size, number of recipients, locations of recipients,availability of recipient (as established by the status monitor 245),speed of transfer, cost and security. The system may vary the cost ofusing the CDNs with time of month based on the amount of bandwidth usedon the CDN. For example, if the CDN contract has a minimum bandwidthusage of 1TB at a fixed price, then as the month goes by, the systemattempts to make sure the 1TB is all used but not exceeded.

If the recipient is currently available, then the file source 230 may beinstructed, if this is the most optimal option based on the criteria, tosend the file directly to the recipient using one of severalPeer-to-Peer (P2P) protocols known in the art 280.1 . . . 280.nresulting in copies of the files in each recipient 235.1 . . . 235.n.

If deemed more efficient based on the criteria, updated copies of thefile in recipients may then be further transmitted using a P2P protocolfrom one file recipient to another instead of from the file source(paths depicted as 281.1 . . . 281.n).

Another possible option, if the file routing server 240 itself is, forexample, within the same Local Area Network (LAN) or Wide Area Network(WAN), then the source 230 may be directed to send 241 the file to thefile routing server 240 where it can be more efficiently retrieved bysome of the intended recipients.

If the file is sent directly to the recipient 235.1 . . . 235.n, thecopy of the file 265 on the origin server 190 may also be updated at alower priority by either the file source 230 or a file recipient 235.1 .. . 235.n, allowing any other file recipient to retrieve the file 260.

Based on the criteria, it may be established that it would be moreoptimal to use the origin server 190 and/or one or more of the CDNs100.1 to 100.m. The file source 230 would then update a copy of its file260 on any number of these delivery systems. Subsequently, any filerecipients can then retrieve the file 260.

The file routing system 200 then updates the file location list 270 toreflect all file transfers.

As there may be a plurality of copies and corresponding paths for a filerecipient to retrieve a copy of a required file, the file routing system200 uses a statistics collector 249 to compile data on, for example,network usage, bandwidth consumed for each CDN and occupancy of theorigin server.

FIG. 3 shows a similar embodiment as shown in FIG. 2, but in this case,a file recipient 330 makes a request for the file 260 which originatedat file source 230 but has already been distributed to existing filerecipient 235.1 . . . 235.n, and to the origin server 190 and possiblyto one or more CDNs 100.1 . . . 100.m. In this case the file recipient330 first sends a network request 310 for the file 260. The file mayhave already been updated to the file routing server 240, to an origincontent server 290 or to any number of CDNs 100.1 . . . 100.m. The filerouting server 240 refers to the file location list 270 as well as a setof criteria to determine an optimal path on which to send a copy of thefile to recipient 330.

Upon the initial request for file 260 (implemented as a networkmessage), the file routing system assesses the criteria to determine theoptimal path for the file transfer for each receiver. The process fordetermining the optimal path is the same as described above.

As described above, it may be using a P2P protocol from the originalsource 230 via network path 380, from a previous recipient 235.1 . . .235.n, from the file routing server 240, or the origin server 190. Asbefore, the choice is made according to the criteria.

If a file recipient requests a file that is in the process of beingtransferred, the file recipient may retrieve the partial file from onelocation (e.g., origin server) and get the rest of the file using a moreefficient path (e.g., P2P).

Optionally, the file routing system 200 may only be used to route filesof a size exceeding a pre-determined threshold while the files ofsmaller size are routed using a fixed path.

The file routing system may prepare plans (criteria, thresholds, etc.)offline using linear programming optimization/simulation based onhistorical usage data. The plan is periodically loaded into the filerouting system to update the criteria and the optimization algorithm.

Network performance enhancement protocols (NPEC) such as TCPacceleration protocols well known in the art, such as the ones describedin U.S. Pat. Nos. 8,630,204 and 9,143,454 and other layer 3 accelerationprotocols as described in U.S. Pat. Nos. 8,437,370, 9,189,307,7,742,501, 8,548,003, 9,953,114 and 8,009,696 may be used to improve theperformance of one or more of the network paths 211.1 . . . 211.m , 241,280.2 . . . 280.m , 212.1 . . . 212.m , 291, 292. The file routingsystem may take into account whether one or more NPEC are enabled on oneor more path as one of or more of the criteria to establish the optimalpath.

One embodiment for establishing the optimal path is now described.

Let set S comprise all possible sources for a given file. For thisexample, the term “source” refers to an origin server, one or more CDNs,and file sources:S={OriginServer, CDN₁, CDN₂, . . . , source_(N)}.

The goal is to find a subset of sources S′<S that maximizes collectiveutility for a number of file recipients accessing the file.

In one embodiment, an exponential utility U function is used :U=e ^(αC) ^(ROI) ^(−C) ^(OPEX) ,

where C^(ROI) is the estimated return on investment from improvingtransfer times, C^(OPEX) is the increase in associated operatingexpenses, and α is a scaling factor to adjust the relative importancebetween the two. Depending on the implementation, the sign of eithercost measure may be either positive or negative,

where C^(OPEX) and C^(ROI) depend on the choice of S′ and can beexpanded as the sum of individual transfers to and from the sources i inS′,C ^(OPEX)=Σ_(i∈S), Σ_(j∈Z) _(i) C _(ij) ^(T) P _(ij)+Σ_(i∈s′) C _(i)^(R),

and where index j runs over all file recipients Z_(i) potentially usingsource i, P_(ij) is the prior probability of file recipient j choosingthe source i, C_(ij) ^(T) is the estimated cost of outbound traffic fromsource i to file recipient j, and C_(i) ^(R) is the cost of datareplication for source i (i.e., inbound traffic and storage). In someimplementations C_(ij) ^(T) and C_(i) ^(R) may also depend on theaverage or burst bit rates experienced by each source, and may be basedon instantaneous values or expected monthly averages.

In one implementation, C^(ROI)=(−1)C^(Time) is used to estimate the lossof revenue due to file recipient dissatisfaction due to longer filetransfer times. In a simplified implementation described below, C^(Time)is taken to be proportional to the transfer time experienced by the filerecipients. In this format U is conveniently bounded between U ∈ (0,1],where maximal utility is achieved in an ideal scenario of zero increasedoperating cost and zero time spent by file recipients.

The total cost due to transfer time may then be summed over all filerecipients,

${C^{Time} = {\sum\limits_{j}^{Z_{i}}C_{ij}^{Time}}},$

where i is understood to indicate the source i ∈ S chosen by the filerecipient, andC _(ij) ^(Time)=β bitrate⁻¹=β RTT_(ij)√{square root over (p _(ij))},

where β is a scaling factor that may be characterized empiricallyrelating the cost to expected transfer bit rate estimated by Mathislimit, and RTT and p stand for round-trip time and packet loss raterespectively between the file recipient and the chosen source.

Since C_(ij) ^(Time) may be calculated between the file recipient andall possible sources i ∈ S, below it is understood that C_(j) ^(Time)stands for the minimal cost possible given the available sources S′C _(j) ^(Time)=min_(i∈s′)(C _(ij) ^(Time)).

In another implementation multiple possible sources are initiallyselected by the file recipient, whose individual costs are weighted bythe probability of choosing themC _(j) ^(Time)=min_(i) ₁ _(,i) ₂ _(∈s′)(C _(i) ₁ _(j) ^(Time) P _(i) ₁_(j) +C _(i) ₂ _(j) ^(Time) P _(i) ₂ _(j)),

where two potential sources i and j are considered. This is convenientfor establishing a probabilistic load balancing scheme to distributetraffic across multiple sources.

Due to linearity of the terms, the logarithm of the utility can beexpressed as sum of costs incurred by individual file recipients, plus aterm relating to the resource replication between sources

$\begin{matrix}{{\ln\; U} = {\left( {- 1} \right)\left( {C^{OPEX} + {\alpha\; C^{Time}}} \right)}} \\{= {{\left( {- 1} \right){\overset{Z}{\sum\limits_{j}}\left( {{\sum\limits_{i \in S^{\prime}}{C_{ij}^{T}P_{ij}}} + {\alpha\; C_{j}^{Time}}} \right)}} - {\sum\limits_{i \in S^{\prime}}C_{i}^{R}}}} \\{{= {{\left( {- 1} \right){\sum_{j}^{Z}C_{j}^{cli}}} - {\sum_{i \in S^{\prime}}C_{i}^{R}}}},}\end{matrix}$

As the number of file recipients increases, the cost of resourcereplication between sources becomes negligible. Further, some CDNproviders to not charge for this type of traffic. With this reduction,log-utility simplifies to sum of cost contributions from each filerecipient jln U=(−1)Σ_(j) ^(z) C _(j) ^(cli),C _(d) ^(cli)=Σ_(i∈s′) C _(ij) ^(Tx) P _(ij) +αC _(j) ^(Time).

Maximal utility is achieved for the subset S′ yielding minimum sum offile recipient costsU_(max)⇔min_(S′∈S)(Σ_(j) ^(Z) C_(j) ^(cli)),

which may be solved numerically by permuting over possible subsets S′⊆S.Since the number of sources is typically up to Θ (10), this task iscomputationally feasible.

In one embodiment, the sum over file recipient costs can be maintainedsimultaneously for each S′ in a dynamic fashion. Consider the full setS₁ ⊆S as a starting point that gives the maximal C^(OPEX) and minimalC^(time), and log-utilityln U ₁=(−1)(Σ_(j) ^(Z) C _(j) ^(cli))_(S) ₁ .

Also, consider the log-utility for a subset S₁⊂S, with source i=1removed.ln U ₂=(−1)(Σ_(j) ^(Z) C _(j) ^(cli))_(S) ₂ ,

which differs from In U₀only due to file recipients for which optimalsource i=1 is absent

$\begin{matrix}{{{\ln\; U_{0}} - {\ln\; U_{1}}} = {\overset{Z}{\sum\limits_{j}}\left( {\Delta\; C_{j}^{cli}} \right)_{S_{1}->S_{2}}}} \\{= {\sum_{j}^{N}{\Delta_{1j}.}}}\end{matrix}$

Generalizing to all W possible subsets S_(i) ⊆S, these deltas areexpressed as a vector

$\begin{matrix}{{\Delta = \left\lbrack {\Delta_{1},\Delta_{2},\Delta_{3},\ldots\mspace{14mu},\Delta_{W}} \right\rbrack},} \\{{= {\sum_{j}^{Z}\left\lbrack {\Delta_{1j},\Delta_{2j},\Delta_{3j},\ldots\mspace{14mu},\Delta_{Wj}} \right\rbrack}},}\end{matrix}$

where the sum is taken across all known file recipient transfers. As newtransfers are introduced, the vector Δ can be updated by summing the newcontributionsΔ_(Z−1)→Δ_(Z−1)+[Δ_(1Z),Δ_(2Z),Δ_(3Z), . . . , Δ_(WZ)].

At any given time, a lookup in Θ(W) can be performed to query theminimum Δ_(i) yielding the subset S_(i) with the maximized utility.

FIG. 4 depicts an example, with an initial start consisting of a fullset of three available sources S₁={s₁, s₂, s₃} 405.1 . . . 405.Z whereZ=3. All possible combinations of sources are hence S₂={s₂, s₃}, S₃={s₁,s₃}, S₄={s₁, s₂}, S₅={s₁}, S₆={s₂} and S₇={s₃}.

The expected contribution to the total cost is calculated for each fourtransfers. These calculations are repeated for all possible sources.FIG. 4 shows the possible paths for the first two file recipients 401,402, where the solid line 403, 404 represents the preferred lowest costpath chosen here purely based on distance from file recipient to source405.1. . . 405.Z.

For each file recipient, we can express the estimated cost in a vectorform having one element for each possible source. For example for filerecipient 1:C₁=[C_(s) ₁ ₁, C_(s) ₂ ₁, C_(s) ₃ ₁]=[0,ΔC_(s) ₂ ₁, ΔC_(s) ₃ ₁].

These costs are used to get a more convenient cost vector spanning allpossible subsets of sources

$\begin{matrix}{{\Delta\; C_{1}^{cli}} = \left\lbrack {\Delta_{11},\Delta_{21},\Delta_{31},\Delta_{41},\Delta_{51},\Delta_{61},\Delta_{71}} \right\rbrack} \\{= \begin{bmatrix}{{\min\left( {0,{\Delta\; C_{s_{2}1}},{\Delta\; C_{s_{3}1}}} \right)},{\min\left( {{\Delta\; C_{s_{1}1}},{\Delta\; C_{s_{3}1}}} \right)},} \\{{\min\left( {0,{\Delta\; C_{s_{3}1}}} \right)},{\min\left( {0,{\Delta\; C_{s_{2}1}}} \right)},0,{\Delta\; C_{s_{2}1}},{\Delta\; C_{s_{3}1}}}\end{bmatrix}} \\{{= \left\lbrack {0,{\Delta\; C_{s_{2}1}},0,0,0,{\Delta\; C_{s_{2}1}},{\Delta\; C_{s_{3}1}}} \right\rbrack},}\end{matrix}$

where the Δ_(i1) is understood to mean the minimum costs for filerecipient 1 given sources S_(i). Repeating this exercise for other filerecipients:ΔC₂ ^(cli)=[0,0,ΔC_(s) ₁ ₂, 0,ΔC_(s) ₁ ₂,0,ΔC_(s) ₃ ₂],ΔC₃ ^(cli)=[0,0, ΔC_(s) ₃ ₃, 0, ΔC_(s) ₁ ₃, 0, ΔC_(s) ₃ ₃],ΔC₄ ^(cli)=[0,0,0, ΔC_(s) ₃ ₄, ΔC_(s) ₁ ₄, ΔC_(s) ₂ ₄, 0].

Finally, summing up the columns across all file recipients, the totalcost for each subset is obtained:

$\begin{matrix}{{\Delta = {\sum_{j}^{4}\left\lbrack {\Delta_{1j},\Delta_{2j},\Delta_{3j},\Delta_{4j},\Delta_{5j},\Delta_{6j},\Delta_{7j}} \right\rbrack}},} \\{{= \begin{bmatrix}{0,{\Delta\; C_{s_{2}1}},\left( {{\Delta\; C_{s_{1}2}} + {\Delta\; C_{s_{3}3}}} \right),{\Delta\; C_{s_{3}4}},} \\\begin{matrix}{\left( {{\Delta\; C_{s_{1}2}} + {\Delta\; C_{s_{1}3}} + {\Delta\; C_{s_{1}4}}} \right),\left( {{\Delta\; C_{{s\;}_{2}1}} + {\Delta\; C_{s_{2}4}}} \right),} \\\left( {{\Delta\; C_{s_{3}1}} + {\Delta\; C_{s_{3}2}} + {\Delta\; C_{s_{3}3}}} \right)\end{matrix}\end{bmatrix}},}\end{matrix}$

from which the subset (element of the vector) with minimized cost can bepicked.

Although the algorithms described above including those with referenceto the foregoing flow charts have been described separately, it shouldbe understood that any two or more of the algorithms disclosed hereincan be combined in any combination. Any of the methods, algorithms,implementations, or procedures described herein can includemachine-readable instructions for execution by: (a) a processor, (b) acontroller, and/or (c) any other suitable processing device. Anyalgorithm, software, or method disclosed herein can be embodied insoftware stored on a non-transitory tangible medium such as, forexample, a flash memory, a CD-ROM, a floppy disk, a hard drive, adigital versatile disk (DVD), or other memory devices, but persons ofordinary skill in the art will readily appreciate that the entirealgorithm and/or parts thereof could alternatively be executed by adevice other than a controller and/or embodied in firmware or dedicatedhardware in a well known manner (e.g., it may be implemented by anapplication specific integrated circuit (ASIC), a programmable logicdevice (PLD), a field programmable logic device (FPLD), discrete logic,etc.). Also, some or all of the machine-readable instructionsrepresented in any flowchart depicted herein can be implemented manuallyas opposed to automatically by a controller, processor, or similarcomputing device or machine. Further, although specific algorithms aredescribed with reference to flowcharts depicted herein, persons ofordinary skill in the art will readily appreciate that many othermethods of implementing the example machine readable instructions mayalternatively be used. For example, the order of execution of the blocksmay be changed, and/or some of the blocks described may be changed,eliminated, or combined.

It should be noted that the algorithms illustrated and discussed hereinas having various modules which perform particular functions andinteract with one another. It should be understood that these modulesare merely segregated based on their function for the sake ofdescription and represent computer hardware and/or executable softwarecode which is stored on a computer-readable medium for execution onappropriate computing hardware. The various functions of the differentmodules and units can be combined or segregated as hardware and/orsoftware stored on a non-transitory computer-readable medium as above asmodules in any manner, and can be used separately or in combination.

While particular implementations and applications of the presentdisclosure have been illustrated and described, it is to be understoodthat the present disclosure is not limited to the precise constructionand compositions disclosed herein and that various modifications,changes, and variations can be apparent from the foregoing descriptionswithout departing from the spirit and scope of an invention as definedin the appended claims.

What is claimed is:
 1. A method for routing a file located on two ormore sources to a plurality of file recipients connected by a pluralityof paths in one or more networks comprising: evaluating for each of theplurality of file recipients one or more predetermined utility functionsthat determines a subset of sources from the two or more sources thatmaximizes collective utility for the plurality of file recipientsaccessing the file to select the most efficient of said plurality ofpaths to use for routing said file to each of said plurality of filerecipients; and routing said file to each of the plurality of filerecipients using said most efficient of said plurality of paths.
 2. Themethod of claim 1 wherein one of the utility functions is the estimatedoperating expense associated with said routing of said file to each ofsaid file recipients.
 3. The method of claim 1 wherein one of theutility functions is the estimated return on investment for improvingsaid routing of said file to each recipient relative to using another ofsaid one or more path.
 4. The method of claim 1 wherein one of theutility functions is related to an estimated file transfer time to eachof said file recipients.
 5. The method of claim 4 wherein said utilityfunction is based on quality of experience for a given file transfer. 6.The method of claim 4 wherein said utility function is based on expectedtransfer bitrate for a given file transfer.
 7. The method of claim 1wherein said evaluating comprises one or more scaling factor to adjustthe relative importance between two or more utility functions.
 8. Themethod of claim 1 wherein a system is used to record a plurality ofhistorical utility metrics associated with the routing of said file toeach of said file recipients.
 9. The method of claim 8 wherein saidevaluating is done probabilistically based on said historical metrics.10. The method of claim 1 further comprising balancing a load betweeneach of the most efficient one of said plurality of paths for each ofsaid file recipients.
 11. A system for routing a file located on two ormore sources to a plurality of file recipients connected by a pluralityof paths in one or more networks comprising: a module coupled with eachof said plurality of file recipients to evaluate one or morepredetermined utility functions that determines a subset of sources fromthe two or more sources that maximizes collective utility for theplurality of file recipients accessing the file to select a mostefficient one of said plurality of paths to use for routing said file tosaid file recipient; said module effecting the routing of said file toeach of the plurality of file recipients using said most efficient oneof said plurality of paths.
 12. The system of claim 11 wherein one ofthe utility functions is the estimated operating expense associated withsaid routing of said file to each of said file recipients.
 13. Thesystem of claim 11 wherein one of the utility functions is the estimatedreturn on investment for improving said routing of said file to eachrecipient relative to using another of said one or more paths.
 14. Thesystem of claim 11 wherein one of the utility functions is related to anestimated file transfer time to each of said file recipients.
 15. Thesystem of claim 14 wherein said utility function is based on quality ofexperience for a given file transfer.
 16. The system of claim 14 whereinsaid utility function is based on expected transfer bit rate for a givenfile transfer.
 17. The system of claim 14 wherein a system is used torecord a plurality of historical utility metrics associated with therouting of said file to each of said file recipients.
 18. The system ofclaim 11 wherein said evaluating comprises one or more scaling factorsto adjust the relative importance between two or more utility functions.19. The system of claim 11 wherein said evaluating is doneprobabilistically based on said historical metrics.
 20. The system ofclaim 11 further comprising balancing a load between each of the mostefficient one of said plurality of paths for each of said filerecipients.